Skin graft Dr.Ahmed Nawres
: Is a segment of dermis and epidermis that has been completely separated from its blood supply (donor site) to be inserted at another site (recipient site).
? It doesn’t have a network of blood vessels.
? (ie it doesn’t have blood supply)
? So need good vascular bed for survival(for take)
? So its bed have to be debrided well
? It survive at the beginning on absorption of plasma like fluid
: While it is detached completely, it remains viable for a limited period of time where precise limit depend on the temperature.
:while the (Flap), has its own blood supply,ie has a network of blood vessels (i.e. it is incompletely separated from its blood supply).,need much more significant surgical technique,need proper planning,more time consuming
: The various processes which result in its reattachment are called (The TAKE).It consists of the following stages:
1st: Plasmatic imbibition (0-3 days).
2nd: Inosculation: linking up of vessels :( 3-7 days).
3rd: Neovascularization: Ingrowth of new blood vessels).
4th:Re-endothelialization.
: Composite graft: composed of 2 tissues, typically skin&cartilage, or skin &fat. It withstands ischemia poorly and success is achieved only under optimal conditions.
(10 mm is the acceptable diameter of the graft, because the surrounding margin can survive 5 mm of the nearby graft ).
Skin graft could be:
1: Auto G: same individual.
2: Allo G: between member of same species.
3: Iso G: between identical twin.
4: Xeno G (Hetero G): between species rather than between members of the
Same species.
Types of SG
1: Partial thickness (split, Hirsh).
2: Full thickness (Wolf).
Partial thickness SG:
: could be: thin, medium, thick.
: cutting instruments: Humby knife, Drum dermatome, Electrical
&air driven dermatome
: could be used in form of: sheet, mesh, and stamp.
: Donor site: wide.
: healing of the donor site: duration: depend on thickness taken,
Usually 2-3 wks.
: Dressing of the donor site: Opsite dressing, or conventional dressing.
: Meshed graft: increase surface area
Drainage
Conform better to irregular contour
Survive better in presence of small pockets of infection
The mesh pattern is detectable when healing is complete
So it should be avoided on face &dorsum of hands.
Full thickness SG:
: After harvesting, we should remove the fat from undersurface of the graft.
: The size that can be harvested is dictated by the closure of the donor site.
: Sites: pre auricular, post auricular, supraclavicular, groin…etc.
Comparism between partial and full thickness SG.
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Split SG
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Full thickness SG
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thickness
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Epidermis &part of dermis
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Epidermis &whole dermis
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Take
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Will take on suboptimal wound bed
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Require well vascularized bed
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Colour &texture match
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less
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More
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contracture
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Tend more to contract
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Little
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Accessory skin structures(adnexae)
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Absent, so it tends to become dry &scaly
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Maintained , but the function return after several months
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Innervations
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earlier
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Better in the long term
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Area available
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large
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Limited
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Causes of SG failure:
1: Inproper contact between graft & bed:
A: Collection: haematoma
Serum
Pus:
Skin graft is contraindicated in the presence of the following:-
Group A beta hemolytic strepto c.
Certain strains of staph.aureus.
Pseudomonas aeroginosa
105 bacteria/gram of tissue.
B: Movement between graft &bed.
C: Inproper tension:
Increase tensionàdrum like effectàinproper contactàgraft failure.
Decrease tensionàwrinkle formationàinproper contactàfailure.
2: Inproper bed: less desirable beds like:
A: cortical bone without periosteum, cartilage without perichondrium,
Tendon without paratenon.
B: irradiated area.
C: fat
D: long standing granulation (e.g. chronic ulcer).
E: old age diabetic, atherosclerotic pt...etc.
3: Application of the graft with the inner side up.
4: Graft held in dependent position.
Uses of SG
àWound cover.
àTreatment of burn:
As permanent cover: auto G.
Iso G: from identical twin
Cadaveric dermis +cultured keratinocytes
? Sandwich graft (auto G + allo G strips).
As temporary cover (i.e. biological dressing):
Allo G, Xeno G, Amnion, Skin substitutes
àClosure of flap donor site.
àMucosal replacement.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .